Pneumatically powered water cannon



July 14, 1970 w. c. COOLEY 3,520,477

I PNEUMATICALLY POWERED WATER CANNON Filed Feb. 23. 1968 FIGI FIGZ

INVENTOR WILLIAM C. COOLEY ATTORNEY United States Patent 3,520,477PNEUMATICALLY POWERED WATER CANNON William C. Cooley, Bethesda, Md.,assignor to Exotech Incorporated, Rockville, Md.

Continuation-impart of application Ser. No. 612,945, Jan. 31, 1967. Thisapplication Feb. 23, 1968, Ser.

Int. Cl. Bb N08 US. Cl. 239-101 3 Claims ABSTRACT OF THE DISCLOSURE Adevice for compressing liquid to extremely high pressures anddischarging it in the form of pulsed jets from a nozzle by means of areciprocating piston in a cylinder. Liquid is supplied under constantpressure to a separate extrusion chamber which communicates with an endface of the cylinder. The free piston is provided with a cylindrical rodhaving an impact surface. The rod extends through one of the end facesof the cylinder apertured for this purpose and communicates with theextrusion chamber to which the liquid is supplied. Pneumatic means isprovided to actuate the free piston driving the same to cause theextension rod to impact the liquid in the extrusion chamber and therebyforce a pulsed jet from a nozzle located therein.

This application is a continuation-in-part of application Ser. No.612,945, entitled Hydraulic Pulse Jet Device, filed Jan. 31, 1967.

This invention relates to devices for producing pulsed jets of liquidfrom a nozzle under extremely high pressures in the order of 50,000 to200,000 p.s.i or higher which is particularly useful for rock-breaking,rock-tunneling, mining, breaking of concrete and a wide variety of otherapplications.

In the past, systems for producing pulsed jets of liquid have utilizedsuch methods as piston expulsion or the cumulation or shaped-chargeprinciple. The piston expulsion theory, utilized in fuel injectiontechniques, offers difficulties with piston sealing and leakage atpressures greater than 3,000 atm. The cumulation principle, that is, thetheory of explosive-shaped charges, has been used for production ofmetallic jets but has not, as yet, been extensively applied forproduction of liquid jets because of the complexity, expense and hazardsin using explosive materials.

Accordingly, it is an object of this invention to provide apneumatically powered hydraulic pulsed jet device for producingrepetitive pulsed jets of liquid with stagnation pressures greater than100,000 p.s.i.

Another object of this invention is to provide a jet pulsing deviceemploying a reciprocating pnematic actuator in conjunction with a highpressure liquid extrusion housing.

Still another object of this invention is to provide a jet pulsingdevice in which a pneumatic actuator cooperates with a high pressureliquid cylindrical housing for ejecting pulsed liquid jets from thecylinder and utilizes only a single valve control for the pneumaticactuator.

It is a further object of this invention to provide a jet pulsing deviceemploying a minimum of parts and which can be constructed in a simpleand economic manner for producing a reliable and continuous operation.

It is still another object of this invention to provide a pulsed jetdevice utilizing a reciprocating pneumatic actuator in combination witha high pressure liquid extrusion housing which is constantly suppliedand kept filled with a liquid independent of the operation of theactuator and wherein the actuator cooperates with the high pressureliquid extrusion cylinder for producing repetitive jet pulses of liquidin the order of 50,000 to 200,000 p.s.i.

According to one embodiment employing the principles of this inventionthere is provided a reciprocating pneumatic actuator comprising acylinder with a reciprocating piston therein. A gas inlet is provided onone side of the piston and a gas outlet on hte other side of the piston.With a valve timer control on the gas inlet and a spring means providedat one end of the cylinder, reciprocation of the piston can becontrolled. The piston is provided with a rod having an impact surfaceextending through an aperture provided in the cylindrical casing.Adjacent this aperture there is provided a high pressure liquidextrusion housing comprising a high pressure cylinder and an end closurewith a nozzle. A suitable liquid inlet means and a liquid drain areprovided to keep the cylinder filled with liquid. When the extension armof the piston enters the high pressure cylinder filled with liquid, ashock wave is generated which moves back and forth in the liquid betweenthe nozzle end and the impact face of the extension arm thereby raisingthe pressure of the liquid therein to a range between 50,000 and 200,000p.s.i. or higher, and, consequently, ejecting a pulsed jet of liquidthrough the nozzle for each stroke of the piston.

Other objects and advantages will become apparent from the followingdetailed study of the specification and drawings, in which:

FIG. 1 is a partial cross-sectional and partial elevational view of theliquid jet pulsing device according to the principles of this invention;and

FIG. 2 illustrates an alternate embodiment of the impact face of theextension rod of the piston.

Referring now to FIG. 1, there is shown a cylindrical housing 2 for thepneumatic actuator. Slida-bly mounted by suitable means, such as gasketsor the like, is a piston member 4 having a centrally extending rod 6.The rod 6 extends through an aperture 8 at one end of the casing 2 and asuitable seal 10 positioned on the periphery of the aperture surroundsthe rod 6 providing a sealing engagement. To the left of the piston 4there is provided in the casing wall a gas inlet port 12. A suitablevalve control 14 is provided therein for regulating the gas flow intothe chamber of the cylindrical housing 2. The valve 14 may be controlledto open and close by a suitable timing means 14a. To the right of thepiston member 4 there is provided a gas outlet port 16. Also to theright of the piston member 4 there is provided a spring 18 of the coiltype, as shown, which is held in place to the right end face of thehousing 2 by an annular recess. The spring 18 coacts with the pistonmember 4 for effecting a return stroke thereto which will be more fullydescribed below.

Adjacent the right end face of the housing 2 there is positioned a highpressure liquid extrusion housing 20 generally of cylindricalconfiguration. The housing 20 consists of an interior chamber 22communicating with a coaxially aligned reduced cross-sectional liquidextrusion chamber 24, the latter having an outlet nozzle 26. The en tirehousing 20 may be bolted by suitable means 28, as shown, to theapertured end face of the pneumatic actuator chamber 2. One or moreliquid inlet ports 30 supply liquid to the extrusion chamber 24 and oneor more liquid drain ports 32 are provided at the periphery of thechamber 22.

The entire device may be reciprocably supported by a support frame whichincludes at one end a suitably perforated encircling annular ring 34provided with two or more bearing means 36 and at the other end apedestal 38 surmounted by a suitable bearing means 40. The encirclingannular ring 34 and the pedestal 38 are connected by a support framestructure 42 which is arranged to be slidably and rigidly supported on arigid support bed plate 44 as shown. Plate 44 may have axially alignedguideways to permit axial recoil motion. Frictional or hydraulic dampingmeans may be provided between the support frame structure 42 and thesupport bed plate 44. The device may be provided at one end by suitablemeans integrally or otherwise with a perforated flange 48 therebyproviding means by which plural hydraulic damping devices 50, 52 may beaflixed between the annular ring 34 and the flange 48, respectively.

The operation of the device is as follows. A flow of com ressed gas, forexample, compressed air, at 50 to 1,000 p.s.i. is supplied to the gasinlet port 12 and hence into the chamber of the housing 2. The piston 4will then accelerate to a velocity of at least 30 ft. per second by thetime the extension rod member 6 reaches the liquid extrusion chamber 24.A liquid, for example, water, is continuously supplied through the inletport 30 communicating with the extrusion chamber 24 thus filling thechamber 22 and the chamber 24 until an overflow occurs through both thenozzle 26 and the drain port 32. When the extension rod 6 of the piston4 enters the chamber 24, a shock wave is generated which moves back andforth in the liquid between the impact face of the extension rod 6 andthe nozzle. This reaction raises the pressure within the chamber 24 to arange between 50,000 and 200,000 p.s.i. or higher, and thus acts toeject a pulsed jet of liquid through the nozzle 26 while at the sametime the piston 4 is decelerating by its coaction with the liquid. Thepiston then comes to rest and by virtue of its engagement with thespring 18 it then effects a return stroke within the bore of the housing2. The piston is stopped and the return stroke is initiated prior toextrusion of all the liquid from the chamber 24, while at the same timethe inlet port 30 is constantly supplying liquid. At approximately thetime of piston impact on the liquid, the gas to the left of the pistonmember 4 will be allowed to escape through the gas outlet port 16, thepiston 4 being positioned to the right of the gas outlet port at thisparticular instance. At this point the valve 14 for the gas inlet 12 isclosed by the timer control means 14a. With the gas inlet port 12closed, the piston, upon its return stroke, will encounter very littleresistance and will therefore return to a position just in front of thegas inlet port 12, at which time the timer control means 14a opens thevalve 14 to initiate another actuating stroke of the piston 4.

As previously mentioned, during the return and the power stroke of thepiston 4, liquid is continually injected into the chambers 24 and 22 inorder that the liquid completely fills the available volume with theexcess draining through the outlet port 32 as well as the nozzle 26.With the chamber 22 continuously filled with liquid, there is no dangerof the piston 4 damaging the device, especially the extrusion housing20, by virtue of impact damage in the absence of any liquid pressure inthe chamber 22 to absorb the shock of the power stroke of piston 4. Tothis end the spring 18 will absorb the shock of the power stroke in theabsence of any liquid in the extrusion housing 20.

In FIG. 2 there is shown an alternate embodiment of the impact face ofthe extension rod 6 of piston 4. Here, the impact face 6a of theextension rod 6 is concave. The concave shape provides focusing of theliquid shock waves in order to achieve higher jet stagnation pressuresthan that ordinarily achieved from the actual pressures acting on thecylinder wall of the chamber 24. It also is contemplated that a suitablegel material may be used as a liquid medium in the manner abovedescribed.

Although several embodiments of the invention have been depicted anddescribed, it will be apparent that these embodiments are illustrativein nature and that a number of modifications in the apparatus andvariations in its end use may be effected.

That which is claimed is:

1. In a device for discharging pulsed liquid jets, the combinationcomprising: a first cylindrical low-pressure casing having end faces andan axial bore, a reciprocable free piston in said bore, one of said endfaces of said casing having means defining an aperture, said aperturehaving a healing means, said piston having an extension rod defining animpact surface and extending through said aperture, a second cylindricalhousing having a highpressure chamber coaxial with said bore of saidfirst housing and having an open face adjacent said apertured end faceof said first housing, the other end face of said second housing havingmeans defining a nozzle communicating with said chamber, means forsupplying liquid to said chamber, and pneumatic means connected to saidfirst cylinder housing for driving said piston, whereby said impactsurface of said extension rod impacts said liquid in said chamber forraising the pressure of said liquid and extruding said liquid from saidnozzle in the form of a pulsed jet having high stagnation pressures.

2. A device for discharging pulsed liquid jets, the combinationcomprising: a first cylindrical low-pressure housing having end faces adan axial bore, a reciprocable free piston in said bore, one of said endfaces having means defining an aperture, said aperture having a sealingmeans, said poston having an extension member defining an impact surfaceand extending through said aperature, a second cylindrical housinghaving an open face adjacent said apertured end face of said firsthousing, said second housing having a cylindrical high-pressure chambertherein coaxial with said bore of said first housing, the other face ofsaid second housing having means defining a nozzle communicating withsaid chamber therein, means supplying liquid to said chamber, andpneumatic means connected to said first housing for driving said piston,whereby said impact surface of said extension member impacts said liquidin said chamber and extrudes said liquid from said nozzle in the form ofa pulsed jet having high stagnation pressures.

3. In a device for discharging pulsed liquid jets, the combinationcomprising: a first cylindrical low-pressure housing having end facesand an axial bore, a reciprocable free piston in said bore, one of saidend faces having means defining an aperture therein, said piston havingan extension rod defining an impact surface and extending through saidaperture, a second cylindrical high-presence housing having an open faceadjacent said apertured end face of said first cylindrical housing, saidsecond cylindrical housing having a first chamber adjacent saidapertured end face, said first chamber having substantially the samediameter as said bore of said first cylindrical housing, a secondchamber in said second cylindrical housing communicating with said firstchamber and having diametrical dimensions substantially corresponding tothe diametrical dimensions of said extension rod, the other end face ofsaid second cylindrical housing having means defining a nozzlecommunicating with said second chamber, means supplying liquid to saidfirst and second chambers, and pneumatic means connected to said firstcylindrical housing for driving said piston, whereby said impact surfaceof said extension rod impacts said liquid in said second chamber andforces said liquid through said nozzle in the form of a pulsed jet.

References Cited UNITED STATES PATENTS 3,412,554 11/1968 Voitsekhovskyet a1. 6054.5

M. H. WOOD 1a., Primary Examiner B. BELKIN, Assistant Examiner US. Cl.X.R.

